About Tailings
Tailings are one of the main by-products of mining, and how they are handled has a direct influence on the safety of nearby communities, the resilience of local ecosystems, and the long-term footprint of a mine. Understanding what tailings are and how they are managed helps explain why they are a central focus of responsible mining practice.
Tailings are produced when ore is crushed and milled into a slurry of water and fine mineral particles. This mixture is usually pumped from the mill to purpose-built storage facilities, often formed using engineered earth dams. As the sandy fraction settles and dries, it can be reclaimed through shaping, covering, and planting vegetation to create a stable landform.
Water in the slurry must be treated before it can be reused or released to local waterways. This treatment helps prevent harmful substances entering the environment or affecting nearby communities. Good management therefore requires attention to both physical stability – keeping the structure sound – and chemical stability – preventing pollution from dust or effluent.
When a facility fails physically, the consequences can be profound. Rapid releases of tailings can inundate landscapes, disrupt livelihoods, and cause loss of life. Past failures have shown why strong standards, rigorous design, and responsible oversight remain vital throughout a facility’s life cycle.
Tailings management
Tailings remain long after mining has ended, and their legacy is shaped by decisions taken throughout the life of an operation. Effective management supports community safety, protects ecosystems, and strengthens trust in the mining sector.
The aftercare needed varies with the properties of the tailings. In some cases, water is drained to support stability before reshaping and revegetation. In more challenging cases, long-term actions are required to maintain both physical and chemical stability.
Although most facilities operate safely, catastrophic tailings dam failures in Canada (Mount Polley in 2015) and Brazil (Samarco in 2015 and Brumadinho in 2019) remind the industry that diligence must be constant. Engineering competence, strong governance, and transparent practice all play critical roles.
The Global Industry Standard on Tailings Management provides a shared framework for safer design, operation, and closure. Developed by ICMM, UNEP, and PRI, it sets clear expectations while allowing operators flexibility in how they meet them.
Types of tailings facilities
Each facility must respond to its specific context – climate, terrain, seismic activity, mineral type, and the presence of nearby communities. Because no two sites are the same, design decisions must be grounded in local realities.
Selecting the most suitable tailings construction method is essential for ensuring a facility operates safely and sustainably. Tailings storage facilities typically use one of three wall construction design: downstream, upstream, or centreline.
Downstream
Downstream designs start with an impervious starter dam. Tailings are then discharged into the dam and as the embankment is raised, each new wall is constructed and supported on top of the downstream slope of the previous section, so the dam crest moves downstream with each raise. The downstream design was developed for areas with seismic activity and high rainfall or water collection.
Upstream
Upstream construction begins with a starter dam. The tailings are then discharged into the facility where they form a tailings beach. The deposited tailings adjacent to the dam wall is allowed to drain and then can be compacted to be used to form the foundation for subsequent levels of the wall as the dam is raised. As such, the crest of the dam moves upstream with each raise.
Upstream tailings dams need to be raised slowly, to allow the solid tailings time to dry and consolidate enough to support a new level of the dam. These are suitable for facilities in areas of low rainfall and low seismic activity.
Centreline
The centreline method is a hybrid of upstream and downstream designs. In centreline construction, the dam is raised vertically from the starter dam. The dam crest therefore remains fixed relative to upstream and downstream directions as the dam is sequentially raised. Internal drainage can be incorporated to improve stability.
Mine Tailings Reduction Goal
Although the majority of facilities are well-managed, the consequences of failures can be severe. Companies therefore look at design, operation, closure, and long-term monitoring as aspects of one continuous responsibility and improvement.
Working toward the goal of zero harm to people and the environment, reducing tailings strengthens environmental protection, enhances safety, and lowers the long term footprint of mining operations, with the added potential to transform waste into value. Because waste rock and tailings make up the vast majority of the sector’s physical waste, even small reductions can deliver meaningful and lasting benefits.
ICMM’s approach mirrors the mitigation hierarchy and is structured around three tracks:
- Reimagine: Preventing the generation of tailings – by exploring alternative mineral recovery methods (a long-term, >15-year goal).
- Reuse: Seeking circular solutions to pursue value in tailings already disposed (a medium-term, 5–10-year goal).
- Reduce: Improvinge operational performance – by enhancing the design ofoperations that can reduce the generation of new tailings.
ICMM's Tailings Innovation Initiative aims to build and support a collaborative ecosystem to help stakeholders accelerate this work.
Cost-effective alternatives to conventionally managed tailings facilities
Advances in geology, mining, and processing technologies are opening new possibilities for reducing, reusing, or transforming tailings. These developments may help lower the volume of material requiring long-term storage.
ICMM’s recent reviews highlight five areas with significant potential:
- Precision geology: Geological techniques, processes or models that have the ability to better characterise the ore body for downstream processing, maximising ore and minimising waste rock being mined which will have an impact on tailings generated.
- Precision mining: Mining approaches or technologies that minimise or eliminate waste rock being mined which will have an impact on tailings generated.
- Precision segregation: Segregation and liberation technologies that are able to optimise metal and mineral recovery or produce more benign tailings.
- In situ and ex situ recovery: Leaching techniques that can optimise metal and mineral recovery and minimise and/or eliminate the volume of waste rock produced which will have an impact on tailings generated.
- Tailings enhancement and valorisation: Different ways to create value from tailings, or ways to minimise the requirement for tailings storage.
ICMM champions collaboration with technology providers, researchers, suppliers, and industry leaders to identify promising innovations and accelerate their adoption. This shared effort supports a mining sector that is safer, more efficient, and better aligned with environmental and community expectations.
